Air-jet spinning machines with appropriately equipped spinning nozzles or spinning stations are known in the prior art (see for example DE 40 36 119 C2) and are used to produce a thread from an elongated fiber sliver. Here, the outer fibers of the fiber sliver are wound around the inner core fibers with the help of a turbulent air flow produced inside the turbulence chamber by means of the air nozzles in the region of the inlet mouth of the thread-forming element and finally form the entwined fibers that are crucial for the required strength of the thread. This results in a thread with a genuine twist that can ultimately be guided out of the turbulence chamber via the take-off channel and wound onto a spool, for example.
In general, within the meaning of the invention, the term thread is therefore understood to mean a fiber sliver with which at least some of the fibers are wound around an inner core. This therefore includes a thread in the conventional sense that can be processed into a material, for example with the help of a web machine. However, the invention also relates to air-jet spinning machines, with the help of which so-called slubbing or roving can be produced. This type of thread is characterized in that, in spite of a certain strength which is sufficient to transport the thread to a downstream textile machine, is still capable of being distorted. The roving can therefore be distorted with the help of a distortion device, e.g. the stretching unit, of a textile machine that processes the roving, for example a ring spinning machine, before it is finally spun.
However, regardless of the strength of the thread, it is always desirable that the twist that is produced in the region of the thread-forming element does not propagate outwards beyond the inlet opening in the opposite direction to the transport direction of the thread or fiber sliver. In other words, it must therefore be ensured that the fibers of the fiber sliver retain their original alignment before coming into contact with the turbulent air flow and only sustain the appropriate twist inside the turbulence chamber. If the twist were to propagate namely in the opposite direction to the transport direction, then the reverse rotation of the fiber sliver would thereby necessarily lead to a reduction in the required entwined fibers and to a reduced ability of the fiber sliver to deform in the region of a deformation unit located before the turbulence chamber.
While a pin pointing in the direction of the thread-forming element is proposed in the above-mentioned publication in order to prevent the said propagation, it is also known to realize the inlet opening of the turbulence chamber by an opening of the so-called fiber guide element, wherein the opening is positioned with a lateral offset with respect to the inlet mouth of the thread-forming element. This results in a shoulder that the fiber sliver must pass before the thread is actually produced, wherein, as a result of the friction between fiber sliver and fiber guide element, the rotation of the fiber sliver is prevented from being able to propagate in the opposite direction to the transport direction.
As with the known solutions, the guide channel is always formed by the fiber guide element that is securely attached to the base body of the spinning nozzle, the spinning nozzle can usually only be used for a certain type of fiber sliver or fibers with a certain length, as the distance between fiber guide element and a delivery roller pair located before the spinning nozzle must usually be matched to a certain fiber length.